Conventionally, a sheet-shaped heat-dissipating member having high thermal conductivity is used inside an electronic device or the like in order to release heat or control the flow of heat in a particular direction. Examples of the electronic device include thermoelectric conversion devices, photoelectric conversion devices, and semiconductor devices such as large scale integrated circuits.
Nowadays, in semiconductor devices, as the miniaturization and densification of the semiconductor devices, and the like proceed, the temperature of heat generated from the inside during operation becomes higher, and when heat dissipation is not sufficient, the properties of the semiconductor devices themselves decrease to sometimes cause malfunction, which may finally lead to the breakage or life decrease of the semiconductor devices. In such a case, as a means to efficiently dissipate, to the outside, heat generated from the semiconductor device, a heat-dissipating sheet having excellent thermal conductivity is provided between the semiconductor device and a heat sink (metal member).
In addition, in thermoelectric conversion devices among such electronic devices, studies of selectively controlling heat dissipation in a particular direction (efficiently providing a temperature difference to the inside of a thermoelectric element) using a sheet-shaped heat-dissipating member, which relate to the control of heat dissipation described above, have been made; because the obtained power increases when heat provided to one face of a thermoelectric element is controlled so that the temperature difference increases in the thickness direction inside the thermoelectric element. Patent Literature 1 discloses a thermoelectric conversion element having a structure as shown in FIG. 7. Specifically, a P-type thermoelectric element 41 and an N-type thermoelectric element 42 are connected in series; thermoelectromotive force extraction electrodes 43 are arranged at both ends thereof to constitute a thermoelectric conversion module 46; and film-shaped substrates 44 and 45 having flexibility composed of two types of materials having different thermal conductivities are provided on both faces of the thermoelectric conversion module 46. In the film-shaped substrates 44 and 45, materials having low thermal conductivity (polyimide) 47 and 48 are provided on the sides of the joining faces to the above thermoelectric conversion module 46, and materials having high thermal conductivity (copper) 49 and 50 are provided on the sides opposite to the joining faces of the above thermoelectric conversion module 46 so as to be positioned in portions of the outer faces of the substrates 44 and 45.
In addition, Patent Literature 2 discloses a thermoelectric conversion module having a structure shown in FIG. 8. Electrodes 54 also serving as high thermal conductivity members are embedded in low thermal conductivity members 51 and 52, and they are arranged on a thermoelectric element 53 via an electrically conductive adhesive layer 55 and an insulating adhesive layer 56.
Further, in Patent Literature 3, as shown in a cross-sectional configuration diagram of a thermoelectric conversion element (the arrangement of a thermoelectric element 61 in the depth direction and internal electrode arrangement are omitted) in FIG. 9, an insulating substratum layer 65 is arranged on one face of the thermoelectric element 61 via an adhesive layer 67; another insulating substratum layer 65 is directly arranged on the other face; and on the substratum layers 65, flexible substrates 62 and 66 having pattern layers comprising metal layers 63 and resin layers 64 are disclosed.